U.S. patent application number 10/591133 was filed with the patent office on 2007-08-23 for method and system for assisting a driver of a vehicle operating a vehicle traveling on a road.
This patent application is currently assigned to Nissan Motor Co., Ltd.. Invention is credited to Takeshi Kimura, Yosuke Kobayashi, Genpei Naito.
Application Number | 20070198136 10/591133 |
Document ID | / |
Family ID | 34917954 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070198136 |
Kind Code |
A1 |
Kobayashi; Yosuke ; et
al. |
August 23, 2007 |
Method and system for assisting a driver of a vehicle operating a
vehicle traveling on a road
Abstract
A system and method for assisting a driver operating a vehicle
traveling on a road includes a scene recognition device detecting
an obstacle in the path of the vehicle. Based on a distance (X) to
the detected obstacle and a vehicle speed (Vh) of the vehicle, a
first target discrimination is effected. Based on the distance (X)
and a relative vehicle speed (Vr) of the vehicle with respect to
the detected obstacle, a second target discrimination is effected.
A first reaction force value (FA1, FB1) is determined versus a
first risk (RP1) from the detected obstacle upon determination, by
the first target discrimination, that the detected obstacle
Inventors: |
Kobayashi; Yosuke;
(Kanagawa-ken, JP) ; Naito; Genpei; (Kanagawa-ken,
JP) ; Kimura; Takeshi; (Kanagawa-ken, JP) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
Nissan Motor Co., Ltd.
|
Family ID: |
34917954 |
Appl. No.: |
10/591133 |
Filed: |
March 2, 2005 |
PCT Filed: |
March 2, 2005 |
PCT NO: |
PCT/JP05/04028 |
371 Date: |
August 30, 2006 |
Current U.S.
Class: |
701/1 ; 701/301;
701/36 |
Current CPC
Class: |
B60W 30/09 20130101;
B60W 10/18 20130101; B60W 2552/00 20200201; B60K 26/021 20130101;
B60T 8/3275 20130101; G01S 17/931 20200101; B60W 2556/50 20200201;
B60T 2201/02 20130101; B60W 50/16 20130101; B60W 2554/00 20200201;
B60K 31/0008 20130101; G08G 1/166 20130101; B60T 2201/03 20130101;
B60W 10/04 20130101; B60W 40/02 20130101 |
Class at
Publication: |
701/001 ;
701/301; 701/036 |
International
Class: |
G06F 7/00 20060101
G06F007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2004 |
JP |
2004-059020 |
Claims
1. A system for assisting a driver operating a vehicle traveling on
a road, the system comprising: a reaction force device that
determines different reaction force values respectively based on
stable information and transient information regarding the vehicle
and an obstacle detected in a path of the vehicle; a driver
controlled input device manually operable by the driver; and an
actuator coupled to the driver controlled input device and
responsive to the reaction force device to selectively transmit the
reaction force values to the driver via a reaction force input from
the driver controlled input device.
2. The system as recited in claim 1, wherein the stable information
includes speed of the vehicle and a distance from the vehicle to
the obstacle, and the transient information includes the distance
from the vehicle to the obstacle and a relative speed of the
vehicle with respect to the obstacle.
3. The system as recited in claim 2, wherein the reaction force
device includes a risk calculation device that determines different
risks based on the stable information and the transient
information.
4. The system as recited in claim 3, wherein the reaction force
device includes a reaction force calculation device that calculates
the different reaction force values as a function of the different
risks respectively.
5. The system as recited in claim 4, wherein the reaction force
device includes a weighting device that weights the reaction force
value based on the transient information, and a reaction force
selection device that selects the reaction force value with the
greatest absolute value from among the reaction force value based
on the stable information and the reaction force value based on the
weighted transient information, the reaction force selection device
providing a signal to the actuator that is indicative of the
selected reaction force value.
6. The system as recited in claim 5, wherein the reaction force
device includes a first target discrimination device that
determines whether the detected obstacle is a target obstacle by
effecting a first target discrimination based on the speed of the
vehicle and the distance from the vehicle to the detected obstacle,
and a second target discrimination device that determines whether
the detected obstacle is a target obstacle by effecting a second
target discrimination based on the distance from the vehicle to the
detected obstacle and the relative speed of the vehicle with
respect to the detected obstacle.
7. The system as recited in claim 6, further comprising: a first
repulsive force calculation device determining a first repulsive
force value versus the first risk; a second repulsive force
calculation device determining a second repulsive force versus the
second risk; a repulsive force selection device selecting the
greatest one, in absolute value, among a set of repulsive force
values including the first and second repulsive force values; a
correction amount calculation device receiving the selected
repulsive force value and determining a correction amount; and a
correction device reducing a driving force applied to the vehicle
in response to the correction amount.
8. The system as recited in claim 7, further comprising: a sensor
detecting a driver power demand; a driving force request generation
device receiving the driver power demand and generating a driving
force request versus the driver power demand; and an engine
controller controlling an engine of the vehicle in response to the
driving force request for generation of the driving force applied
to the vehicle; and wherein the correction device modifies, in
response to the determined correction amount, a relationship
between the generated driving force and the driver power demand in
a direction of providing a reduction in the driving force.
9. The system as recited in claim 7, further comprising: a sensor
detecting a driver brake demand; a braking force request generation
device receiving the driver brake demand and generating a braking
force request versus the driver brake demand; and a brake
controller controlling a brake system of the vehicle in response to
the braking force request for generation of a braking force applied
to the vehicle; and wherein the correction device modifies a
relationship between the generated braking force and the driver
brake demand in a direction of providing an increase in the braking
force.
10. The system as recited in claim 5, wherein the weighting device
performs the weighting of the reaction force value based on the
transient information when the different risks are each greater
than a predetermined value.
11. The system as recited in claim 5, wherein the weighting device
performs the weighting of the reaction force value based on the
transient information when the reaction force value is based on the
transient information is greater than the reaction force value
based on the stable information and the different risks are each
greater than a predetermined value.
12. The system as recited in claim 5, wherein the weighting device
performs the weighting of the reaction force value based on the
transient information if the weighted reaction force based on the
transient information is greater than the reaction force value
based on the stable information and that the different risks are
each greater than a predetermined value,
13. The system as recited in claim 5, further comprising a scene
recognition device that detects an obstacle in the path of the
vehicle, the scene recognition device determining whether the
obstacle is stationary or in motion, and wherein the weighting
device performs the weighting of the reaction force value based on
the transient information heavier upon determination that the
obstacle is in motion than it does upon determination that the
obstacle is stationary.
14. The system as recited in claim 5, further comprising a scene
recognition device that detects an obstacle in the path of the
vehicle, the scene recognition device determining whether or not
the obstacle is being decelerated, and wherein the weighting device
performs the weighting of the reaction force value based on the
transient information heavier upon determination that the obstacle
is being decelerated than it does upon determination that the
obstacle is not being decelerated.
15. The system as recited in claim 6, wherein the first target
discrimination device determines that the detected obstacle is the
target obstacle when a time headway (THW), which is obtained by
dividing the distance by the vehicle speed, is less than a first
threshold value, and wherein the second target discrimination
device determines that the detected obstacle is the target obstacle
when a time to collision (TTC), which is obtained by dividing the
distance by the relative vehicle speed, is less than a second
threshold value.
16. The system as recited in claim 1, wherein the driver controlled
input device includes at least one of an accelerator pedal and a
brake pedal.
17. The system as recited in claim 3, wherein the risk calculation
device includes first and second risk calculation devices that
respectively calculate first and second risks as the different
risks, and the reaction force calculation devices includes first
and second reaction force calculation devices that respectively
calculate first and second reaction force values as the different
reaction force values, the system further comprising: a first
contact possibility discrimination device determining whether or
not the vehicle may come into contact with the detected obstacle by
effecting contact possibility discrimination based on the distance
and the vehicle speed; a third risk calculation device determining
a third risk from the detected obstacle upon determination, by the
first contact possibility discrimination device, that the vehicle
may come into contact with the detected obstacle; a third reaction
force calculation device determining a third reaction force value
versus the third risk; a second contact possibility discrimination
device determining whether or not the vehicle may come into contact
with the detected obstacle by effecting contact possibility
discrimination based on the distance and the relative vehicle
speed; a fourth risk calculation device determining a fourth risk
from the detected obstacle upon determination, by the second
contact possibility discrimination device, that the vehicle may
come into contact with the detected obstacle; and a fourth reaction
force calculating device determining a fourth reaction force value
versus the fourth risk, and wherein the set of reaction force
values includes the third and fourth reaction force values in
addition to the first reaction force value and the weighted second
reaction force value, whereby the reaction force selection device
selects the greatest one among the first reaction force value, the
weighted second reaction force value, the third reaction force
value, and the fourth reaction force value.
18. A vehicle, comprising: a scene recognition device detecting an
obstacle in the path of the vehicle; a first target discrimination
device determining whether or not the detected obstacle is a target
obstacle by effecting a first target discrimination based on a
vehicle speed of the vehicle and a distance to the detected
obstacle from the vehicle; a first risk calculation device
determining a first risk from the detected obstacle upon
determination, by the first target discrimination device, that the
detected obstacle is the target obstacle; a first reaction force
calculation device determining a first reaction force value versus
the fist risk; a second target discrimination device determining
whether or not the detected obstacle is a target obstacle by
effecting a second target discrimination based on the distance to
the detected obstacle and a relative vehicle speed of the vehicle
with respect to the detected obstacle; a second risk calculation
device determining a second risk from the detected obstacle upon
determination, by the second target discrimination device, that the
detected obstacle is the target obstacle; a second reaction force
calculation device determining a second reaction force value versus
the second risk; a weighting device performing a weighting of the
second reaction force value; a reaction force selection device
selecting the greatest one, in absolute value, among a set of
reaction force values including the first reaction force value and
the weighted second reaction force value and providing an output
signal indicative of the selected reaction force value; a driver
controlled input device manually operable by a driver; and an
actuator coupled to the driver controlled input device and
operative in response to the output signal to transmit the selected
reaction force value to the driver via a reaction force input from
the driver controlled input device.
19. A method for assisting a driver operating a vehicle traveling
on a road, the method comprising: detecting an obstacle in the path
of the vehicle; determining whether or not the detected obstacle is
a target obstacle by effecting a first target discrimination based
on a vehicle speed of the vehicle and a distance to the detected
obstacle from the vehicle; determining a first risk from the
detected obstacle upon determination, by the first target
discrimination, that the detected obstacle is the target obstacle;
determining a first reaction force value versus the first risk;
determining whether or not the detected obstacle is a target
obstacle by effecting a second target discrimination based on the
distance to the detected obstacle and a relative vehicle speed of
the vehicle with respect to the detected obstacle; determining a
second risk from the detected obstacle upon determination, by the
second target discrimination, that the detected obstacle is the
target obstacle; determining a second reaction force value versus
the second risk; performing a weighting of the second reaction
force value; selecting the greatest one, in absolute value, among a
set of reaction force values including the first reaction force
value and the weighted second reaction force value and providing an
output signal indicative of the selected reaction force value;
transmitting the selected reaction force value indicated by the
output signal to the driver via a reaction force input from a
driver controlled input device manually operable by the driver.
20. A system for assisting a driver operating a vehicle traveling
on a road, the system comprising: means for detecting an obstacle
in front of the vehicle; means for conducting one of different
analyses of the detected obstacle to provide one of different
partially overlapped periods allowing determination of a risk
derived from the detected obstacle to give a variable; means for
selecting one out of concurrently occurring ones of the variables
to interconnect the variables into a final variable existing over
at least two adjacent different periods; and means for transmitting
the final variable to the driver via a haptic input.
Description
RELATED APPLICATION
[0001] The present application claims the benefit of priority from
Japanese Patent Application No. 2004-59020, filed Mar. 3, 2004,
which application is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] 1. Field of the Invention
[0003] The present invention relates to a method and system for
assisting a driver operating a vehicle traveling on a road.
[0004] 2. Background Art
[0005] The conventional art describes systems for assisting a
driver operating a vehicle traveling on a road.
[0006] JP10-166889A discloses a driver assisting system, which,
when a distance to a preceding vehicle drops to a predetermined
value, sets an increased magnitude of a reaction force from an
accelerator pedal. JP10-166890A discloses a similar driver
assisting system. JP2000-54860A discloses a driver assisting
system, which, when an automatic control is being carried out, sets
an increased magnitude of a reaction force from an accelerator
pedal. US 2003/0163240 A1, published Aug. 28, 2003, discloses a
driver assisting system, which adjusts a reaction force from an
accelerator pedal upon detection of a discontinuous change in
environment around a vehicle. JP2003-1901830A discloses a driver
assisting system by performing brake control based on results of
calculation of a time-to-collision (TTC) with respect to each
obstacle in the path of a vehicle in a manner to avoid unsmooth
changes in braking force.
[0007] US 2003/0060936 A1, published Mar. 27, 2003, discloses a
driver assisting system. This system comprises a data acquisition
system acquiring data including information on status of a vehicle
and information on environment in a field around the vehicle, a
controller, and at least one actuator. The controller determines a
future environment in the field around the vehicle using the
acquired data, for making an operator response plan in response to
the determined future environment, which plan prompts the operator
to operate the vehicle in desired manner for the determined future
environment. The actuator is coupled to a driver controlled input
device to mechanically affect operation of the input device in a
manner that prompts, via a haptic input from the driver controlled
input device, the driver to operate the vehicle in the desired
manner.
[0008] A need remains for an improved method and system that
provides a driver with transient information that a vehicle is
approaching an obstacle as well as stable information that the
vehicle is following the obstacle in front of the vehicle.
[0009] An object of the present invention is to provide a method
and system that meets the above-mentioned need.
SUMMARY OF INVENTION
[0010] According to one aspect of the present invention, there is
provided a system for assisting a driver operating a vehicle
traveling on a road. This system comprises a reaction force device
that determines different reaction force values respectively based
on stable information and transient information regarding the
vehicle and an obstacle detected in a path of the vehicle. A driver
controlled input device is provided that is manually operable by
the driver. An actuator is coupled to the driver controlled input
device and responsive to the reaction force device to selectively
transmit the reaction force values to the driver via a reaction
force input from the driver controlled input device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a block diagram of an embodiment of the system
according to embodiments of the present invention.
[0012] FIG. 2 is a perspective view of a motor vehicle equipped
with the system according to embodiments of the present
invention.
[0013] FIG. 3 is a schematic diagram of an actuator coupled with a
driver controlled input device to transmit varying of an output
signal to a driver via a reaction force from a manually operable
pedal.
[0014] FIG. 4 is a state diagram of a vehicle equipped with the
system according to embodiments of the present invention traveling
along a two-lane road with two obstacles (preceding vehicles) in
front of the vehicle.
[0015] FIG. 5 is a block diagram of a driving force controller with
a correction device indicated as a summation point.
[0016] FIG. 6 shows a driving force request (Fda) versus driver
power demand (SA, an accelerator pedal position) characteristic
provided by a driving force request generation device of the
driving force controller.
[0017] FIG. 7 is a block diagram of a braking force controller with
a correction device indicated as a summation point.
[0018] FIG. 8 shows a braking force request (Fdb) versus driver
brake demand (SB, a brake pedal position) characteristic provided
by a braking force request generation device of the braking force
controller.
[0019] FIG. 9 is a block diagram of a controller of the system
shown in FIG. 1.
[0020] FIG. 10 is a flow chart of a main control routine
illustrating the implementation of the operation of the embodiment
shown in FIG. 1.
[0021] FIG. 11 is a flow chart of a target discrimination
subroutine.
[0022] FIG. 12 is a state diagram of a vehicle traveling on a road
with a preceding vehicle in front of the vehicle, illustrating the
concept of an imaginary elastic body used for calculation of a risk
(RP) derived from the preceding vehicle and a repulsive force
(Fc).
[0023] FIG. 13 is the state diagram of the vehicle having
approached the preceding vehicle when the risk grows.
[0024] FIG. 14 is a flow chart of a risk (RP) calculation
subroutine.
[0025] FIG. 15 is a flow chart of a weighting subroutine.
[0026] FIG. 16 shows varying of a weighting multiplier with
different values of a vehicle speed of the preceding vehicle.
[0027] FIG. 17 shows varying of another weighting multiplier with
different values of an acceleration of the preceding vehicle.
[0028] FIG. 18 is a flow chart of a reaction force calculation
subroutine.
[0029] FIG. 19 shows varying of an accelerator pedal reaction force
(FA) with different values of the risk (RP).
[0030] FIG. 20 shows varying of a brake pedal reaction force (FB)
with different values of the risk (RP).
[0031] FIG. 21 is a flow chart of a repulsive force calculation
subroutine.
[0032] FIG. 22 shows varying of a repulsive force (Fc) with
different values of the risk (RP).
[0033] FIG. 23 is a flow chart of a reaction force selection
subroutine.
[0034] FIG. 24 is a flow chart of a repulsive force selection
subroutine.
[0035] FIG. 25 is a flow chart of a correction amount calculation
subroutine.
[0036] FIG. 26 shows varying of a driving force correction amount
with elapse of time after release of an accelerator pedal.
[0037] FIG. 27 shows varying of a braking force correction amount
with elapse of time after release of the accelerator pedal.
[0038] FIG. 28 shows, in solid lines, the corrected versions of the
normal driving force request (Fda) versus accelerator pedal
position (SA) characteristic and the normal braking force request
(Fdb) versus brake pedal position (SB), respectively, shown, in a
one-dot chain line.
[0039] FIG. 29 is a state diagram of the vehicle, equipped with an
embodiment of the system, traveling on a road with a preceding
vehicle in front of the vehicle, illustrating the concept of two
different imaginary elastic bodies used for calculation of two
different risks (RP1, RP2) derived from the preceding vehicle and
two different repulsive forces (Fc1, Fc2).
[0040] FIGS. 30(a) to 30(f) are time charts illustrating the
operation of the embodiment of the system according to the present
invention.
[0041] FIG. 31 is a block diagram, similar to FIG. 1, of another
embodiment of the system according to the present invention.
[0042] FIG. 32 is a block diagram, similar to FIG. 9, of a
controller of the embodiment shown in FIG. 31.
[0043] FIG. 33 is a flow chart, similar to FIG. 15, of a weighting
subroutine.
[0044] FIG. 34 is a block diagram of a modified controller, which
may be used in the system shown in FIG. 1.
[0045] FIG. 35 is a flow chart, similar to FIG. 10, of a main
routine illustrating the implementation of operation of the system
using the modified controller shown in FIG. 34.
[0046] FIG. 36 is a flow chart of a contact possibility
discrimination subroutine.
[0047] FIG. 37 is a flow chart, similar to FIG. 14, of a risk (RP)
calculation subroutine.
[0048] FIG. 38 is a flow chart, similar to FIG. 18, of a reaction
force calculation subroutine.
[0049] FIG. 39 is a flow chart, similar to FIG. 21, of a repulsive
force calculation subroutine.
[0050] FIG. 40 is a flow chart, similar to FIG. 23, of a reaction
force selection subroutine.
[0051] FIG. 41 is a flow chart, similar to FIG. 24, of a repulsive
force selection subroutine.
DETAILED DESCRIPTION OF THE INVENTION
[0052] The present invention provides a system, denoted generally
by reference numeral 1 in FIG. 1 or reference numeral 2 in FIG. 31
using controller 50 (see FIG. 9) or controller 50B (see FIG. 34),
for assisting a driver operating a vehicle traveling on a road. The
system 1 or 2 comprises a scene recognition device 8 (see FIG. 1)
or 8A (see FIG. 31) detecting an obstacle in front of the vehicle
5. The system 1 or 2 comprises at least two subsystems. In FIG. 9,
the at least two subsystems include a first subsystem 51a, 52a,
54a, and 55a, and a second subsystem 51b, 52b, 53, 54b, and 55b. In
FIG. 34, the at least two subsystems include, in addition to the
first and second subsystems, a third subsystem 51c, 52c, 54c, and
55c, and a fourth subsystem 51d, 52d, 54d, and 55d. As the
discussion proceeds, it will be understood that each of the at
least two subsystems conducts one of different analyses of the
detected obstacle at one of the blocks labeled "target
discrimination devices" 51a and 51b (see FIGS. 9 and 34) and blocks
labeled "contact possibility discrimination devices" 51c and 51d.
As the discussion proceeds, it may well be understood that
conducting one of different analyses of the detected obstacle
provides one of different partially overlapped periods allowing
determination of a risk RP1 or RP2 derived from the detected
obstacle to give a variable (FA1, FB1, Fa2, Fb2, Fc1 or Fc2, see
FIG. 9; FA3, FB3, FA4, FB4, Fc3, or Fc4, see FIG. 34). A selection
device selects one out of concurrently occurring ones of the
variables to produce out of the variables a final variable existing
over at least adjacent two of the different period. The final
variable (FA, FB or Fc) is transmitted to the driver via a haptic
input, such as a reaction force from a driver controlled input
device or a change in acceleration/deceleration of the vehicle.
[0053] The term "target discrimination" will be herein used to mean
one of different analyses of data from the scene recognition device
8 (or 8A) regarding the detected obstacle(s) in front of the
vehicle 5 to determine whether or not the detected obstacle is a
target obstacle to be treated for further processes that follow in
one of the subsystems. Similarly, the term "contact possibility
discrimination" will be herein used to mean one of different
analyses of data from the scene recognition device 8A regarding the
detected obstacle(s) in front of the vehicle 5 to determine whether
or not there is a high possibility that the vehicle 5 may come into
contact with the detected obstacle. If this is the case, the
detected obstacle is a target obstacle to be treated for further
processes that follow in one of the subsystems.
[0054] The accompanying drawings illustrate various exemplary
embodiments of a method and system according to the present
invention. Like reference numerals are used throughout each Figure
to designate like parts or portions. FIGS. 1 to 30(f) are used
below for description of one embodiment. FIGS. 31 to 33 are used
later for description of another embodiment, and FIGS. 34 to 41 for
description of the modified controller.
[0055] Turning now to FIGS. 1 and 2, the scene recognition device 8
includes a radar 10 positioned at a center of a front grill or a
front bumper of the vehicle 5 (see FIG. 2) for transmitting pulsed
beam or radar waves ahead of the vehicle in order to detect
obstacles within the field of view of the radar. Although it may be
a conventional millimeter wave, frequently modulated continuous
(FMCW) radar, the radar 10, in this embodiment, is a conventional
infrared laser radar. An infrared pulsed beam travels, as a
transmitted beam, toward a measurement zone. A light receiving
device receives the transmitted beam returning from an obstacle
inside the measurement zone. With the use of a rotating polygonal
mirror, two-dimensional scanning in the forward direction is
possible, so that the pulsed beam can be swiveled horizontally due
to the rotation of the polygonal mirror, and the pulsed beam can be
swiveled vertically a plurality of mirror surfaces of the polygonal
mirror inclined at different angles. In the exemplary embodiment,
the pulsed beam can be swiveled horizontally and laterally about 6
degrees to each side of a longitudinal line passing through the
center of the vehicle 5.
[0056] The scene recognition device 8 may include a camera, Global
Positioning System (GPS) device, a navigation device, and any other
appropriate devices capable of providing data useful for
recognition of environment around the vehicle 5 along with
detection of obstacle(s) in front of the vehicle 5.
[0057] Based on the time delay and phase difference between the
transmitted beam from the laser radar 10 and the received reflected
beam, a control logic can determine a distance and azimuth angle
between each of the detected obstacle(s) and the vehicle 5. The
control logic may be implemented within the scene recognition
device 8 or a controller 50.
[0058] This step of determination may be better understood by
referring to the state diagram of FIG. 4. The vehicle 5 is shown
traveling along a two-lane road. A plurality of obstacles OB1 and
OB2 are shown in front of the vehicle 5. These obstacles are
determined to be at a distance X1, X2, and at an azimuth angle
.theta.1=0, .theta.2, respectively from the vehicle 5.
[0059] The controller 50 processes data generated by the scene
recognition device 8 and vehicle dynamics, such as vehicle speed Vh
from a vehicle speed sensor 20.
[0060] The vehicle speed sensor 20 may determine the vehicle speed
Vh by processing outputs from wheel speed sensors. The vehicle
speed sensor 20 may include an engine controller or a transmission
controller, which can provide a signal indicative of the vehicle
speed.
[0061] The controller 50 may contain a microprocessor including as
usual a central processing unit (CPU), and computer readable
storage medium, such as a read only memory (ROM), a random access
memory (RAM). The computer readable storage medium contains
computer readable instructions thereon to implement at least two
subsystems of the system 1. Each of the at least two subsystems
provides one of different analyses of the detected obstacle to
provide one of different at least partially overlapped periods.
Example of the different partially overlapped periods is
illustrated in FIG. 30(d). In FIG. 30(d), one period ends at moment
tb and the adjacent partially overlapped period begins at moment
ta. The provided one period allows determination of a risk (RP1 or
RP2) to give a variable (Fa2, FA1, Fc2, Fc1, see FIG. 30(f) and
FIG. 30(e)). A selection device (56, 57) selects one out of
concurrently occurring ones of the variables (during overlapped
time from ta to tb, see FIG. 30(e)) to interconnect the variables
(Fc1, Fc2) into a final variable (Fc) existing over at least
adjacent two of the different periods.
[0062] In order to transmit the final variable FA to the driver via
a haptic input from a driver controlled input device in the form of
an accelerator pedal 62, an actuator 61 coupled to the accelerator
pedal 62 is activated to produce a reaction force under the control
of an accelerator pedal reaction force controller 60 that operates
in response to the control signal FA.
[0063] The final variable FA indicates an accelerator pedal
reaction force value determined by the controller 50. In response
to the final variable FA, the accelerator pedal reaction force
controller 60 regulates operation of the actuator 61. The actuator
61 is in the form of a servomotor mechanically coupled to the
accelerator pedal 62. FIG. 3 shows one example of the accelerator
pedal 62 with the servomotor 61 and the accelerator pedal stroke
sensor 64. For understanding of the driver controlled input device,
reference should be made to US 2003/0236608 A1 (published Dec. 25,
2003) and also to US 2003/0233902 A1 (published Dec. 25, 2003),
both of which have been hereby incorporated by reference in their
entireties.
[0064] An accelerator pedal stroke sensor 64 is provided to detect
an angular position of the servomotor 61 linked to the accelerator
pedal 62. As the angular position of the servomotor 61 varies with
different positions of the accelerator pedal 62, the accelerator
pedal stroke sensor 64 can generate a sensor signal indicative of a
driver power demand SA expressed via the accelerator pedal 62. The
sensor signal indicative of the driver power demand SA is fed to
the accelerator pedal reaction force controller 60 for position
control of the servomotor 61. The sensor signal indicative of the
driver power demand SA is fed also to a driving force controller 63
in the conventional manner for calculation of a control signal to
an engine 66.
[0065] In order to transmit the final variable FB to the driver via
a haptic input from a driver controlled input device in the form of
a brake pedal 92, an actuator 91 coupled to the brake pedal 92 is
activated to produce a reaction force under the control of a brake
pedal reaction force controller 90 that operates in response to the
final variable FB.
[0066] The final variable FB indicates a brake pedal reaction force
value determined by the controller 50. In response to the final
variable FB, the brake pedal reaction force controller 90 regulates
operation of the actuator 91. The actuator 91 is in the form of a
servomotor mechanically coupled to the brake pedal 92 in the same
manner as the servomotor 61 is coupled with the accelerator pedal
62 (see FIG. 3). The actuator 91 may be in the form of a computer
controlled hydraulic brake assist system that is capable of
regulating a power assist.
[0067] A brake pedal stroke sensor 94 is provided to detect an
angular position of the servomotor 91 linked to the brake pedal 92.
As the angular position of the servomotor 91 varies with different
positions of the brake pedal 92, the brake pedal stroke sensor 94
can generate a sensor signal indicative of a driver brake demand SB
expressed via the brake pedal 62. The sensor signal indicative of
the driver brake demand SB is fed to the brake pedal reaction force
controller 90 for position control of the servomotor 91. The sensor
signal indicative of the driver brake demand SB is fed also to a
braking force controller 93 in the conventional manner for
calculation of a control signal to a hydraulic brake system 96. As
shown in FIG. 2, the hydraulic brake system 96 includes wheel
brakes 95.
[0068] The system 1 may optionally provide a haptic input to the
driver by modifying operation of the engine 66 of the vehicle 5 via
the driving force controller 63 and/or by modifying operation the
hydraulic brake system 96 of the vehicle 5 via the braking force
controller 93. In order to create the haptic input acceptable to
the driver, the controller 50 processes the data generated by the
accelerator pedal stroke sensor 64 and brake pedal stroke sensor 94
to assure an appropriate change in relationship between the driver
power demand SA and driving force applied to the vehicle 5 and/an
appropriate change in relationship between the driver brake demand
SB and braking force applied to the vehicle 5.
[0069] With continuing reference to FIG. 1, the controller 50
provides a correction signal indicative of a driving force
correction amount .DELTA.Da to the driving force controller 63 and
a correction signal indicative of a braking force correction amount
.DELTA.Db to the braking force controller 93.
[0070] The block diagram of FIG. 5 illustrates the driving force
controller 63 with a correction device 63b as indicated by a
summation point. The driving force controller 63 includes a driving
force request generation device 63a and an engine controller 63c.
The driving force request generation device 63a receives the driver
power demand SA and provides a driving force request Fda by data
processing to realize the driving force request (Fda) versus driver
power demand (SA) characteristic illustrated in FIG. 6. The driving
force request Fda is fed to the correction device 63b. At the
correction device 63b, the driving force request Fda is modified by
the driving force correction amount .DELTA. Da to provide the
modified result as a target driving force tDF. In response to the
target driving force tDF, the engine controller 63c provides an
engine control signal applied to the engine 66 to accomplish the
corrected characteristic as illustrated by the fully drawn line in
FIG. 28.
[0071] The block diagram of FIG. 7 illustrates the braking force
controller 93 with a correction device 93b as indicated by a
summation point. The braking force controller 93 includes a braking
force request generation device 93a and a brake fluid pressure
controller 93c. The braking force request generation device 93a
receives the driver brake demand SB and provides a braking force
request Fdb by data processing to realize the braking force request
(Fdb) versus driver brake demand (SB) characteristic illustrated in
FIG. 8. The braking force request Fdb is fed to the correction
device 93b. At the correction device 93b, the braking force request
Fdb is modified by the braking force correction amount .DELTA.Db to
provide the modified result as a target braking force tFdb. In
response to the target braking force tFdb, the brake fluid pressure
controller 93c determines a brake fluid pressure and provides a
brake control signal applied to the hydraulic brake system 96 to
accomplish the corrected characteristic as illustrated by the fully
drawn line in FIG. 28.
[0072] The implementation of the method and system according to the
present invention can best be explained using the block diagram of
FIG. 9. As mentioned before, the at least two subsystems of the
system 1 include a first subsystem 51a, 52a, 54a, and 55a, and a
second subsystem 51b, 52b, 53, 54b, and 55b. The distance and
azimuth angle .theta. between each of the detected obstacle(s) and
the vehicle 5, and the vehicle speed Vh are fed to a first target
discrimination device 51a of the first subsystem and a second
target discrimination device 51b of the second subsystem. They are
fed also to a first risk (RP) calculation device 52a of the first
subsystem and to a second risk (RP) calculation device 52b of the
second subsystem.
[0073] The system 1 has introduced two notions, namely, a time
headway THW and a time to collision TTC, and provides two different
analyses of the detected obstacle at the first and second target
discrimination devices 51a and 51b to provide two different
partially overlapped periods, respectively.
[0074] In the first subsystem, the first target discrimination
device 51a determines whether or not the detected obstacle is a
target obstacle by effecting a first target discrimination based on
the vehicle speed Vh of the vehicle 5 and a distance X to the
detected obstacle from the vehicle 5. Specifically, the first
target discrimination device 51a determines that the detected
obstacle is the target obstacle when the time headway THW is less
than a first threshold value Th1, for example, 1.5 seconds. Upon
determination that the detected obstacle is the target obstacle,
the first target discrimination device 51a activates a first risk
(RP) calculation device 52a, a first reaction force calculation
device 54a, and a first repulsive force calculation device 55a.
[0075] In the second subsystem, the second target discrimination
device 51b determines whether or not the detected obstacle is a
target obstacle by effecting a second target discrimination based
on a relative vehicle speed Vr of the vehicle 5 to the detected
obstacle and the distance X. Specifically, the second target
discrimination device 51b determines that the detected obstacle is
the target obstacle when the time to collision TTC is less than a
second threshold value Th2, for example, 10 seconds. Upon
determination that the detected obstacle is the target obstacle,
the second target discrimination device 51b activates a second risk
(RP) calculation device 52b, a second reaction force calculation
device 54b, and a second repulsive force calculation device
55b.
[0076] When it is activated, each of the first and second risk
calculation devices 52a and 52b determines a risk (RP) derived from
the target obstacle. Referring to FIGS. 12 and 13, the manner of
determining a risk (RP) is described.
[0077] The state diagram of FIG. 12 illustrates the vehicle 5
traveling on a road with a target obstacle in the form of a
preceding vehicle in front of the vehicle 5. Assuming that the
vehicle 5 has an imaginary elastic body extending from the front
bumper forwardly toward the preceding vehicle, a model considered
is that the imaginary elastic body is compressed between the
vehicle body 5 and the preceding vehicle as shown in FIG. 13 to
generate a pseudo running resistance against the vehicle 5. The
risk (RP) derived from the preceding vehicle may be defined as a
spring force applied to the vehicle by the imaginary elastic body
compressed between the vehicle 5 and the preceding vehicle, and may
be expressed as: RP=k.times.(L-X). (Equation 1)
[0078] where: k is the spring constant of the imaginary elastic
body, L is an unstressed length of the imaginary elastic body, and
X is a distance between the vehicle 5 and the preceding
vehicle.
[0079] The risk (RP) derived from the preceding vehicle is 0 (zero)
when the distance X exceeds the length L as in the state of FIG.
12. After the imaginary elastic body has come into contact with the
preceding vehicle, the imaginary elastic body is compressed so that
the risk (RP) becomes great as the distance X becomes short.
[0080] Turning back to the block diagram of FIG. 9, the first risk
(RP) calculation device 52a determines a risk derived from the
target obstacle and provides the determined risk, as a first risk
RP1. The first risk RP1 is fed to the first reaction force
calculation device 54a and also to the first repulsive force
calculation device 55a. In the embodiment, the first reaction force
calculation device 54a determines, as variables, a first
accelerator pedal reaction force value FA1 versus the first risk
RP1 by using the illustrated relationship of FIG. 19 and also a
first brake pedal reaction force value FB1 versus the first risk
RP1 by using the illustrated relationship of FIG. 20. The first
repulsive force calculation device 55a determines, as a variable, a
first repulsive force value Fc1 versus the first risk RP1 by using
the illustrated relationship of FIG. 22.
[0081] The second risk (RP) calculation device 52b determines a
risk derived from the target obstacle and provides the determined
risk, as a second risk RP2. The second risk RP2 is fed to the
second reaction force calculation device 54b and also to the second
repulsive force calculation device 55b. In the embodiment, the
second reaction force calculation device 54b determines, as
variables, a second accelerator pedal reaction force value Fa2
versus the second risk RP2 by using the illustrated relationship of
FIG. 19 and also a second brake pedal reaction force value Fb2
versus the second risk RP2 by using the illustrated relationship of
FIG. 20. The second repulsive force calculation device 55b
determines, as a variable, a second repulsive force value Fc2
versus the second risk RP2 by using the illustrated relationship of
FIG. 22.
[0082] Determination of the first risk RP1 is allowed during a
stable period when the vehicle 5 follows the preceding vehicle (or
obstacle) in front. Determination of the second risk RP2 is allowed
during a transient period partially overlapping the state period.
The first risk RP1 may be called a stable risk, and the second risk
RP2 a transient risk. The repulsive force is a force applied by an
imaginary elastic body compressed between the vehicle 5 and the
preceding vehicle in front. The imaginary elastic body was briefly
mentioned in connection with FIGS. 12 and 13, but will be further
described later in connection with FIG. 29.
[0083] The second subsystem also includes a weighting device 53.
The weighting device 53 processes the data from the scene
recognition device 8 to determine the amount of weighting used for
performing a weighting of each of the second reaction force values
Fa2 and Fb2 to provide, as variables, a weighted second accelerator
pedal reaction force value FA2 and a weighted second brake pedal
reaction force value FB2.
[0084] The first and the weighted second accelerator pedal reaction
force values FA1 and FA2, and the first and the weighted second
brake pedal reaction force values FB1 and FB2 are fed to the
reaction force selection device 56. Following a predetermined rule,
the reaction force selection device 56 selects an appropriate one
of the first and the weighted second accelerator pedal reaction
force values FA1 and FA2 and provides the selected one as a
accelerator pedal reaction force (APRF) indicative final variable
FA. The final variable FA is fed to the accelerator pedal reaction
force controller 60 (see FIG. 1). In the same manner, the reaction
force selection device 56 selects one of the first and the weighted
second brake pedal reaction force values FB1 and FB2 and provides
the selected one as a brake pedal reaction force (BPRF) indicative
final variable FB. The final variable FB is fed to the brake pedal
reaction force controller 90 (see FIG. 1).
[0085] The first and second repulsive force values Fc1 and Fc2 are
fed to a repulsive force selection device 57. The repulsive force
selection device 57 selects an appropriate one of the first and
second repulsive force values Fc1 and Fc2 and provides the selected
one, as a repulsive force (RF) indicative final variable Fc. The
repulsive force indicated by the final variable Fc is regarded as a
pseudo running resistance to the vehicle 5. The final variable Fc
is fed to a correction amount calculation device 58. Regarding the
final variable Fc as the running resistance, the correction amount
calculation device 58 determines a driving force correction amount
.DELTA.Da and a braking force correction amount .DELTA.Db. The
correction amount calculation device 58 provides the determined
driving and braking force correction amounts .DELTA.Da and
.DELTA.Db to the driving and braking force controllers 63 and 93,
respectively (see FIG. 1).
[0086] In the exemplary embodiment, the controller 50 implements
all of the devices of the block diagram shown in FIG. 9 in
software.
[0087] FIG. 10 is a flow chart of a main control routine
illustrating the operation of the embodiment of the system
according to the present invention. In the embodiment, the
controller 50 repeats execution of the main control routine at
regular intervals of, for example, 50 milliseconds.
[0088] In FIG. 10, at step S100, the controller 50 performs reading
operation to receive, as inputs, data (distance X, azimuth angle
.theta.) generated by the scene recognition device 8, vehicle
dynamics, such as vehicle speed Vh from the vehicle speed sensor
20, and driver demands, such as driver power demand SA from the
accelerator pedal stroke sensor 64 and driver brake demand SB from
the brake pedal stroke sensor 94.
[0089] At step S200, the controller 50 recognizes the state of
obstacle(s) relative to the vehicle 5 from a relative position of
each obstacle to the vehicle 5, and a direction and a speed of
travel of the obstacle, which are obtained by processing the
present and past data obtained at step S100. The controller 50 thus
selects the obstacle in the path of the vehicle 5 and recognizes
the state of the selected obstacle from its position, its travel
direction, and its travel speed relative to the vehicle 5.
[0090] At step S300, the controller 50 executes a target
discrimination sub-routine shown in FIG. 11 to determine whether or
not the detected obstacle is a target obstacle.
[0091] Referring to the target discrimination sub-routine of FIG.
11, at step S301, the controller 50 calculates a time headway THW
between each of the detected obstacles and the vehicle 5. The time
headway THW may be expressed as: THW=X/Vh (Equation 2) At the same
step S301, the controller 50 calculates a time to collision TTC
between each of the detected obstacles and the vehicle speed 5. The
time to collision TTC may be expressed as: TTC=-X/Vr (Equation
3)
[0092] where: Vr is a relative vehicle speed given by subtracting a
vehicle speed Vh of the vehicle 5 from a speed of the detected
obstacle.
[0093] At step S302, the controller 50 determines whether or not
the time headway THW between the detected obstacle and the vehicle
5 is greater than or equal to the first threshold value Th1, for
example, 1.5 seconds. If this is the case, that is, THW is not less
than Th1, the controller 50 determines that the detected obstacle
is not a target obstacle and sets a THW target flag Flg_thw to 0
(Flg_thw=0) at step S303. If, at step S302, the time headway THW is
less than Th1, the controller 50 determines that the detected
obstacle is a target obstacle and sets the THW target flag Flg_thw
to 1 (Flg_thw=1) at step S304. After step S303 or S304, the routine
proceeds to step S305.
[0094] At step S305, the controller 50 determines whether or not
the time to collision TTC between the detected obstacle and the
vehicle 5 is greater than or equal to the second threshold value
Th2, for example, 10 seconds. If this is the case, that is, TTC is
not less than Th2, the controller 50 determines that the detected
obstacle is not a target obstacle and sets a TTC target flag
Flg_ttc to 0 (Flg_ttc=0) at step S306. If, at step S305, the time
to collision TTC is less than Th2, the controller 50 determines
that the detected obstacle is a target obstacle and sets the TTC
target flag Flg_ttc to 1 (Flg_ttc=1) at step S307. After step S306
or S307, the routine proceeds to step S400 (see FIG. 10).
[0095] At step S400, the controller 50 executes a risk (RP)
calculation sub-routine of FIG. 14 to determine a first risk RP1
upon determination that the detected obstacle is a target obstacle
due to the fact that time headway THW is less than the first
threshold value Th1, and also to determine a second risk RP2 upon
determination that the detected obstacle is a target obstacle due
to the fact that time to contact TTC is less than the second
threshold value Th2. Referring to the state diagram of FIG. 29, it
is now assumed that the vehicle 5 has two different imaginary
elastic bodies extending from the front bumper forwardly toward the
preceding vehicle.
[0096] With continuing reference to FIG. 29, the risk (RP)
calculation sub-routine shown in FIG. 14 is described.
[0097] In FIG. 14, at step S401, the controller 50 determines
whether or not the THW target flag Flg_thw is equal to 1. If this
is the case, the routine proceeds to step S402 because the detected
obstacle is a target object.
[0098] At step S402, the controller 50 determines an unstressed
length L1 of a first one of the two different imaginary elastic
bodies using the first threshold value Th1 and the vehicle speed
Vh. The unstressed length L1 may be expressed as: L1=Th1.times.Vh
(Equation 4)
[0099] At step S403, the controller 50 determines the first risk
RP1, which may be expressed as: RP1=k1.times.(L1-X). (Equation
5)
[0100] where: k1 is a spring constant of the first imaginary
elastic body.
[0101] If, at step S401, the THW target flag Flg_thw is 0, the
routine proceeds to step S404 because the detected obstacle is not
a target obstacle. At step S404, the controller 50 sets the first
risk RP1 to 0 (RP1=0). As mentioned before, the first risk RP1 may
be called a stable risk. After step S403 or S404, the routine
proceeds to step S405.
[0102] At step S405, the controller 50 determines whether or not
the TTC target flag Flg_ttc is equal to 1. If this is the case, the
routine proceeds to step S406 because the detected obstacle is a
target object.
[0103] At step S406, the controller 50 determines an unstressed
length L2 of a second one of the two different imaginary elastic
bodies using the second threshold value Th2 and the relative
vehicle speed Vr. The unstressed length L2 may be expressed as:
L2=Th2.times.Vr (Equation 6) At step S407, the controller 50
determines the second risk RP2, which may be expressed as:
RP2=k2.times.(L2-X). (Equation 7)
[0104] where: k2 is a spring constant of the second imaginary
elastic body.
[0105] If, at step S405, the TTC target flag Flg_ttc is 0, the
routine proceeds to step S408 because the detected obstacle is not
a target obstacle. At step S408, the controller 50 sets the second
risk RP2 to 0 (RP2=0). As mentioned before, the second risk RP2 may
be called a transient risk. After step S407 or S408, the routine
proceeds to step S500 (see FIG. 10).
[0106] At step S500, the controller 50 executes a weighting
sub-routine of FIG. 15 to determine an appropriate weighting for
clear transmission of the second or transient risk RP2 to the
driver of the vehicle 5 via reaction force inputs from the
accelerator pedal 62 and brake pedal 92. Specifically, the
controller 50 determines a weighting multiplier K.
[0107] In FIG. 15, at step S501, the controller 50 calculates a
vehicle speed Vt of the preceding vehicle in front of the vehicle 5
by processing the data obtained at step S100. At step S502, the
controller 50 calculates an acceleration, a, of the preceding
vehicle by processing the present and past data of the vehicle
speed Vt. At step S503, the controller determines whether the
vehicle speed Vt of the preceding vehicle is greater than a
predetermined vehicle speed value of, for example, 5 km/h. If this
is the case, the controller 50 determines that the preceding
vehicle is in motion and the routine proceeds to step S504. At step
S504, the controller 50 determines a weighting multiplier value
K_vt versus the vehicle speed Vt of the preceding vehicle by using
the illustrated relationship in FIG. 16. The solid line in FIG. 16
clearly shows that the weighting multiplier value K_vt gradually
increases from the value of 1 as the vehicle speed Vt of the
preceding vehicle increases beyond the predetermined vehicle speed
value Vt0. After step S504, the routine proceeds to step S505.
[0108] At step S505, the controller determines whether or not the
acceleration a of the preceding vehicle is less than 0. If this is
the case, the controller determines that the preceding vehicle is
under deceleration and the routine proceeds to step S506. At step
S506, the controller 50 determines another weighting multiplier
value K_a versus the acceleration a of the preceding vehicle by
using the illustrated relationship in FIG. 17. The solid line in
FIG. 17 clearly shows that the weighting multiplier value K_a
gradually increases from the value of 1 as the acceleration a
decreases after it has become less than 0.
[0109] At the next step S507, the controller 50 determines the
weighting multiplier K as the product of the multiplier values of
K_vt and K_a. The weighting multiplier K may be expressed as:
K=K.sub.--vt.times.K.sub.--a (Equation 8)
[0110] The routine proceeds to step S508 from step S503 or step
S505 if the interrogation results are negative. At step S508, the
controller 50 sets the weighting multiplier K to 1.
[0111] After determining the weighting multiplier K, the routine
proceeds from step S500 to step S600.
[0112] At step S600, the controller 50 executes a reaction force
calculation sub-routine of FIG. 18 to determine, as variables,
first accelerator pedal and brake pedal reaction force values FA1,
FB1 and the weighted second accelerator pedal and brake pedal
reaction force values FA2 and FB2.
[0113] In FIG. 18, at step S601, the controller 50 determines a
first accelerator pedal reaction force value FA1 versus the first
or stable risk RP1 by using the relationship illustrated in FIG.
19. The solid line in FIG. 19 clearly shows that the accelerator
pedal reaction force value FA is proportional to the risk RP over a
range where the risk RP is less than a predetermined value RPmax
but not less than 0 (zero). After the risk RP has reached the
predetermined value RPmax, the accelerator pedal reaction force
value FA is fixed to a predetermined maximum value FAmax and thus
invariable with different values of risk RP greater than the
predetermined value RPmax.
[0114] At step S602, the controller 50 determines a second
accelerator pedal reaction force value Fa2 versus the second or
transient risk RP2 by using the relationship illustrated in FIG.
19.
[0115] At step S603, the controller 50 determines a first brake
pedal reaction force value FB1 versus the first or stable risk RP1
by using the relationship illustrated in FIG. 20. The solid line in
FIG. 20 clearly shows that the brake pedal reaction force value FB
is inversely proportional to the risk RP over a range where the
risk RP is less than the predetermined value RPmax but not less
than 0 (zero). After the risk RP has reached the predetermined
value RPmax, the brake pedal reaction force value FB is fixed to a
predetermined minimum value FAmax and thus invariable with
different values of risk RP greater than the predetermined value
RPmax.
[0116] At step S604, the controller 50 determines a second brake
pedal reaction force value Fb2 versus the second or transient risk
RP2 by using the relationship illustrated in FIG. 20.
[0117] As is readily seen from FIG. 19, when the risk RP is less
than the predetermined value RPmax, varying of the risk RP is
transmitted to the driver via one of different reaction force
values from the accelerator pedal. On the other hand, when the risk
RP is greater than or equal to the predetermined value RPmax, the
reaction force value is maximized, prompting the driver to
releasing the accelerator pedal 62. At the same time, the brake
pedal reaction force is minimized as shown in FIG. 20 to make it
easy for the driver to step on the brake pedal 92.
[0118] At step S605, the controller 50 performs a weighting of each
of the second accelerator pedal reaction force value Fa2 and second
brake pedal reaction force value Fb2 to give a weighted second
accelerator pedal reaction force value FA2 and a weighted second
brake pedal reaction force value FB2. The weighted second
accelerator pedal and brake pedal reaction force values FA2 and FB2
may be expressed as: FA2=K.times.Fa2 (Equation 9) FB2=K.times.Fb2
(Equation 10)
[0119] After determining the first and the weighted second
accelerator pedal and brake pedal reaction force values FA1, FB1,
FA2 and FB2 at step S600, the routine proceeds to step S700.
[0120] At step S700, the controller 50 executes a repulsive force
calculation sub-routine of FIG. 21.
[0121] In FIG. 21, at step S701, the controller 50 determines, as a
variable, a first repulsive force value Fc1 versus the first or
stable risk RP1 by using the relationship illustrated in FIG. 22.
The solid line in FIG. 22 clearly shows that the repulsive force Fc
is proportional to the risk RP over a range where the risk RP is
less than a predetermined value RPmaxl but not less than 0 (zero).
After the risk RP has reached the predetermined value RPmaxl, the
repulsive force Fc is fixed to a predetermined maximum value Fcmax
and thus invariable with different values of risk RP greater than
the predetermined value RPmaxl.
[0122] At the next step S702, the controller 50 determines, as a
variable, a second repulsive force value Fc2 versus the second or
transient risk RP2 by using the relationship illustrated in FIG.
22.
[0123] After determining the repulsive force values Fc1 and Fc2 at
step S700, the routine proceeds to step S800.
[0124] At step S800, the controller 50 executes a reaction force
selection sub-routine of FIG. 23.
[0125] In FIG. 23, at step S801, the controller 50 determines
whether or not the first accelerator pedal reaction force value FA1
is greater than or equal to the weighted second accelerator pedal
reaction force value FA2. If this is the case, the routine proceeds
to step S802. At step S802, the controller 50 selects the first
accelerator pedal reaction force value FA1 as an accelerator pedal
reaction force indicative final variable FA. If, at step S801, the
first accelerator pedal reaction force value FA1 is less than the
weighted second accelerator pedal reaction force value FA2, the
routine proceeds to step S803. At step S803, the controller 50
selects the weighted second accelerator pedal reaction force value
FA2 as the final variable FA. After selecting the greatest or
highest one among a set of reaction force values including the
first accelerator pedal reaction force value FA1 and the weighted
second accelerator pedal reaction force value FA2 as the final
variable FA, the routine proceeds to step S804.
[0126] At step S804, the controller 50 determines whether or not
the first brake pedal reaction force value FB1 is greater than or
equal to the weighted second brake pedal reaction force value FB2.
If this is the case, the routine proceeds to step S805. At step
S805, the controller 50 selects the weighted second brake pedal
reaction force value FB2 as a brake pedal reaction force indicative
final variable FB. If, at step S804, the first brake pedal reaction
force value FB1 is less than the weighted second brake pedal
reaction force value FB2, the routine proceeds to step S806. At
step S806, the controller 50 selects the first brake pedal reaction
force value FB1 as the final variable FB. After selecting the
lowest one among a set of reaction force values including the first
brake pedal reaction force value FB1 and the weighted second brake
pedal reaction force value FB2 as the final variable FB, the
routine proceeds to step S900.
[0127] At step S900, the controller 50 executes a repulsive force
selection sub-routine of FIG. 24.
[0128] In FIG. 24, at step S901, the controller 50 determines
whether or not the first repulsive force value Fc1 is greater than
or equal to the second repulsive force value Fc2. If this is the
case, the routine proceeds to step S902. At step S902, the
controller 50 selects the first repulsive force value Fc1 as a
repulsive force indicative final variable Fe. If, at step S901, the
first repulsive force value Fc1 is less than the second repulsive
force value Fc2, the routine proceeds to step S903. At step S903,
the controller 50 selects the second repulsive force value Fc2 as
the final variable Fc. After selecting the greatest one among a set
of repulsive force values including the first repulsive force value
Fc1 and the second repulsive force value Fc2 as the final variable
Fc, the routine proceeds to step S1000.
[0129] At step S1000, the controller 50 executes a correction
amount calculation sub-routine of FIG. 25.
[0130] In FIG. 25, at step S1001, the controller 50 determines
whether or not the accelerator pedal 62 is pressed from the driver
power demand SA from the accelerator pedal stroke sensor 64. If the
accelerator pedal 62 is not pressed, the routine proceeds to step
S1002. At step S1002, the controller 50 determines whether or not
the accelerator pedal 62 has been released quickly. This
determination is made by comparing operation speed of the
accelerator pedal 62 to a predetermined value. The operation speed
may be calculated from a time rate of change in driver power demand
SA from the accelerator pedal stroke sensor 64. If, at step S1002,
the controller 50 determines that the accelerator pedal 62 has been
slowly released, the routine proceeds to step S1003. At step S1003,
the controller 50 sets a driving force correction amount .DELTA.Da
to 0 (.DELTA.Da=0). At the next step S1004, the controller 50 sets
a braking force control amount .DELTA.Db to the repulsive force
indicative final variable Fe.
[0131] If, at step S1002, the controller 50 determines that the
accelerator pedal 62 has been quickly released, the routine
proceeds to step S1005. At step S1005, the controller 50 carries
out a decrement of the driving force correction amount .DELTA.Da
for gradual decrement of the driving force correction amount
.DELTA.Da toward 0. At the next step S1006, the controller 50
carries out an increment of the braking force correction amount
.DELTA.Db for gradual increment of the braking force correction
amount .DELTA.Db toward the final variable Fe.
[0132] If, at step S1001, the controller 50 determines that the
accelerator pedal 62 is pressed, the routine proceeds to step
S1007. At step S1007, the controller 50 determines a driving force
request Fda versus driver power demand SA by using the relationship
illustrated in FIG. 6 and generates the determined driving force
request Fda.
[0133] At the next step S1008, the controller 50 determines whether
or not the driving force request Fda is greater than or equal to
the repulsive force control value Fc. If this is the case, the
routine proceeds to step S1009. At step S1009, the controller 50
sets the driving force correction amount .DELTA.Da to -Fc
(.DELTA.Da=-Fc). At the next step S1010, the controller 50 sets the
braking force correction amount .DELTA.Db to 0 (.DELTA.Db=0). In
this case, the driver feels acceleration less than expected because
the driving force request Fda still remains after it has been
reduced by Fc.
[0134] If, at step S1008, the controller 50 determines that the
driving force request Fda is less than the final variable Fc, the
routine proceeds to step S1011. At step S1011, the controller 50
sets the driving force correction amount .DELTA.Da to -Fda
(.DELTA.Da=-Fda). At the next step S1012, the controller 50 sets
the braking force correction amount .DELTA.Db to a compensation
(Fc-Fda) for a shortage in the driving force correction amount. In
this case, the driver feels deceleration.
[0135] FIG. 28 illustrates the manner of correcting driving force
and braking force. In FIG. 28, the horizontal axis represents the
accelerator pedal position or driver power demand SA and the brake
pedal position or driver brake demand SB. The driver power demand
SA increases from the origin 0 in a right-hand direction. The
driver brake demand SB increases from the origin 0 in a left-hand
direction. The vertical axis represents the driving force and the
braking force. The driving force increases from the origin 0 in an
upward direction. The braking force increases from the origin 0 in
a downward direction.
[0136] In FIG. 28, the one-dot chain line indicates varying of
driving force request Fda with different values of accelerator
pedal position SA and varying of braking force request Fdb with
different values of brake pedal position SB.
[0137] The solid line indicates varying of driving and braking
force requests as corrected by the correction amounts .DELTA.Da and
.DELTA.Db.
[0138] When the driving force request Fda is greater than the
repulsive force indicative final variable Fc, the driving force
request Fda is decreased simply by the driving force correction
amount .DELTA.Da (=-Fc).
[0139] When the driving force request Fda is less than the final
variable Fc, the driving force request Fda is decreased by the
driving force correction amount .DELTA.Da (=-Fda), leaving no
driving force request. The braking force correction amount
.DELTA.Db is set to a difference between the final variable Fc and
the driving force request Fda. In this case, the driver feels less
rapid deceleration corresponding to restrained driver power demand
SA.
[0140] After calculating the driving force and braking force
correction amounts .DELTA.Da and .DELTA.Db, the routine proceeds to
step S1100.
[0141] Turning back to FIG. 10, at step S1100, the controller 50
provides the accelerator pedal reaction force indicative final
variable FA and the brake pedal reaction force indicative final
variable FB to the accelerator pedal reaction force controller 60
and the brake pedal reaction force controller 90, respectively (see
FIG. 1). The accelerator pedal reaction force controller 60
regulates a reaction force from the accelerator pedal 62 in
accordance with the final variable FA. The brake pedal reaction
force controller 90 regulates a reaction force from the brake pedal
92 in accordance with the final variable FB.
[0142] At the next step S1200, the controller 50 provides the
driving force correction amount .DELTA.Da and braking force
correction amount .DELTA.Db to the driving force controller 63 and
braking force controller 93, respectively. The driving force
controller 63 calculates a target driving force based on the
driving force correction amount .DELTA.Da and the driving force
request Fda, and controls the engine to generate the target driving
force. The braking force controller 93 calculates a target braking
force based on the braking force correction amount .DELTA.Db and
driving force request Fdb, and controls a hydraulic brake fluid
pressure to generate the target braking force.
[0143] With reference now to FIG. 29 and FIGS. 30(a) to 30(f), the
embodiment of the method and system according to the present
invention can best be explained.
[0144] FIG. 29 shows first and second imaginary elastic bodies
extending from the vehicle 5 toward the preceding vehicle in front
of the vehicle 5. The first imaginary elastic body has an
unstressed length L1 and a spring constant k1, while the second
imaginary elastic body has an unstressed length L2 and a spring
constant k2. When the first imaginary elastic body is compressed
between the vehicle 5 and the preceding vehicle, the first or
stable risk RP1 is generated. When the second imaginary elastic
body is compressed between the vehicle 5 and the preceding vehicle,
a second or transient risk RP2 is generated.
[0145] FIGS. 30(a) to 30(c) are time charts illustrating the state
of the vehicle 5 approaching and then following the preceding
vehicle in front, with varying of vehicle speed Vh, relative speed
Vr, distance X, risks RP1 & RP2, repulsive force indicative
final variable Fc, and accelerator pedal reaction indicative final
variable FA.
[0146] As shown in FIGS. 30(a), 30(b) and 30(c), the vehicle speed
Vh and distance X gradually decrease, while the relative speed Vr
gradually increases. Specifically, at or immediately after moment
ta, the distance X becomes equal to or less than a predetermined
distance. Subsequently, at or immediately after moment tb, relative
speed Vr becomes equal to or greater than zero. After the moment
ta, the distance X stays less than the predetermined distance until
it converges into the predetermined distance.
[0147] Until the moment tb, relative speed Vr stays less than 0 and
continues to approach 0 at a gradual rate. The result of one
analysis that the time to collision TTC stays less than Th2
(TTC<Th2) provides a transient period allowing determination of
transient risk RP2. Partially overlapping the transient period, the
result of another different analysis that the time headway THW
stays less than Th1 (THW<Th1) provides a stable period allowing
determination of stable risk RP1.
[0148] As shown in FIG. 30(e), the second repulsive force value Fc2
and the first repulsive force value Fc1 exist concurrently with the
transient risk RP2 and the stable risk RP1, respectively. The fully
drawn line in FIG. 30(e) shows varying of the repulsive force
indicative final variable Fc obtained after the selection out of
the repulsive force values Fc2 and Fc1.
[0149] As shown in FIG. 30(f), the fully drawn line shows varying
of the accelerator pedal reaction force indicative final variable
FA obtained after the selection out of the weighted reaction force
value FA2 and the reaction force value FA1.
[0150] In the case where the vehicle 5 is approaching the preceding
vehicle, firstly, the weighted reaction force value FA2 is
generated during the transient period before generation of the
reaction force FA1 during the state period. It is therefore
possible to clearly transmit the transient risk RP2 at an early
stage of approaching the preceding vehicle. The repulsive force
value Fc2 is not weighted so as to prevent excessive correction of
driving force and/or braking force.
[0151] An increase in relative speed Vr due to a change in the
vehicle speed Vh of the vehicle 5 or the speed Vt of the preceding
vehicle can be clearly transmitted to the driver because the
reaction force value Fa2 is weighted before being transmitted.
[0152] The embodiment can be appreciated again from reading the
following description:
[0153] (1) With reference to FIG. 9, the first target
discrimination device 51a determines whether or not the detected
obstacle is a target obstacle based on a distance X between the
vehicle 5 and the detected obstacle and a speed Vh of the vehicle
5. The first or stable risk (RP) calculation device 52a determines
a first or stable risk RP1 upon determination by the first target
discrimination device 51a that the detected obstacle is the target
obstacle. In response to the state risk RP1, the first reaction
force calculation device 54a determines first accelerator and brake
pedal reaction force values FA1 and FB1.
[0154] The second target discrimination device 51b determines
whether or not the detected obstacle is a target obstacle based on
the distance X and a relative speed Vr between the vehicle 5 and
the detected obstacle. The second or transient risk (RP2)
calculation device 52 determines a second or transient risk RP2
upon determination by the second target discrimination device 51b
that the detected obstacle is the target obstacle. In response to
the transient risk RP2, the second reaction force calculation
device 54b determines second accelerator and brake pedal reaction
force values Fa2 and Fb2. The weighting device 53 performs a
weighting of the second accelerator and brake pedal reaction force
values Fa2 and Fb2 to give weighted second reaction force values
FA2 and FB2.
[0155] The reaction force selection device 56 selects the greatest
or highest one, in absolute value, among a set of reaction force
values including the first accelerator pedal reaction force value
FA1 and the weighted second accelerator pedal reaction force value
FA2 and/or the greatest or highest one, in absolute value, among a
set of reaction force values including the first brake pedal
reaction force value FB1 and the weighted second brake pedal
reaction force value FB2.
[0156] The controller 50 provides the selected ones, as final
variables FA and FB, for adjustment of reaction forces from the
driver controlled input devices toward the reaction force values
indicated by the final variables FA and FB. This makes it possible
to clearly transmit the transient risk RP2 to the driver well
before transmission of the stable risk RP1.
[0157] (2) The first repulsive force calculation device 55a
determines a first repulsive force value Fc1 versus the state risk
RP1. The second repulsive force calculation device 55b determines a
second repulsive force value Fc2 versus the transient risk RP2. The
repulsive force selection device 57 selects the larger one of the
repulsive force values Fc1 and Fc2. The controller 50 provides the
selected one, as final variable Fc, for an appropriate reduction in
driving force as if it were caused due to occurrence of running
resistance due to the repulsive force indicated by the final
variable Fc. Acceleration/deceleration control caused due to this
reduction in driving force provides a haptic input to the driver as
a clear assist. Weighting is not performed in producing the
repulsive force indicative final variable Fc in order to avoid an
unnecessary large change in driving force control.
[0158] (3) As explained before in connection with FIG. 28, the
controller 50 can correct, via the driving force controller 63, the
driving force request Fda versus driver power demand SA
characteristic in a direction of reducing driving force based on
the repulsive force indicative final variable Fc. An appreciable
drop in driving force occurs in response to increased possibility
that the vehicle may contact with the detected obstacle,
transmitting the increased possibility to the driver via a
reduction in acceleration or deceleration.
[0159] (4) As explained before in connection with FIG. 28, the
controller 50 can correct, via the braking force controller 93, the
braking force request Fdb versus brake power demand SB
characteristic in a direction of increasing braking force based on
the repulsive force indicative final variable Fc. Increased
possibility that the vehicle may contact with the detected obstacle
is transmitted to the driver upon stepping on the brake pedal via
an increase in braking force corresponding to a braking force
correction amount .DELTA.Db.
[0160] (5) The controller 50 performs a weighting of the second
reaction force values Fa2 and Fb2 when both the stable risk RP1 and
the transient risk RP2 are greater than or equal to a predetermined
value. Referring to FIG. 30(d), in the embodiment, the controller
50 performs a weighting of the reaction force values Fa2 and Fb2
that are determined versus the transient risk RP2 during a time
from ta to tb. The weighted second reaction force values FA2 and
FB2 are selected in preference to the first reaction force values
FA1 and FB1 determined versus the stable risk RP1, allowing the
transient risk RP2 to be transmitted to the driver clearly.
[0161] (6) The controller 50 performs a weighting of the second
reaction force values Fa2 and Fb2 when both the stable risk RP1 and
the transient risk RP2 are greater than or equal to a predetermined
value and the second reaction force values Fa2 and Fb2 determined
versus the transient risk RP2 are greater, in absolute value, than
the first reaction force values FA1 and FB1 determined versus the
stable risk RP1. Referring to FIG. 30(f), in the exemplary
embodiment, the controller 50 performs a weighting of the second
reaction force values Fa2 and Fb2 during a time from ta to tc. The
transient risk RP2 can be transmitted to the driver clearly and
impressively via the weighted second reaction force values Fa2 and
Eb2.
[0162] (7) The controller 50 performs a weighting of the second
reaction force values Fa2 and Fb2 when both the stable risk RP1 and
the transient risk RP2 are greater than or equal to a predetermined
value and if the weighted second reaction force values FA2 and FB2
are greater than the first reaction force values FA1 and FB1.
Referring to FIG. 30(f), in the exemplary embodiment, the
controller 50 performs a weighting of the second reaction force
values Fa2 and Fb2 during a time from ta to td. The weighted second
reaction force values FA2 and FB2 determined versus the transient
risk RP2 are selected in preference to the first reaction force
values FA1 and FB1 determined versus the state risk RP1, allowing
the transient risk RP2 to be transmitted to the driver clearly.
[0163] (8) The controller 50 performs a weighting of the second
reaction force values Fa2 and Fb2 to give the weighted second
reaction force values FA2 and FB2 upon recognition that the
preceding vehicle is in motion or moving, making it possible to
transmit to the driver an increased risk due to the preceding
vehicle in motion.
[0164] (9) The controller 50 performs a weighting of the second
reaction force values Fa2 and Fb2 to give the weighted second
reaction force values FA2 and FB2 upon recognition that the
preceding vehicle is under deceleration, making it possible to
transmit to the driver an increased risk due to the preceding
vehicle in motion.
[0165] (10) The first target discrimination device 51a determines
that the detected obstacle is a target obstacle when a time headway
(THW), which is obtained by dividing the distance by the vehicle
speed, is less than a first threshold value Th1, and the second
target discrimination device 51b determines that the detected
obstacle is a target obstacle when a time to collision (TTC), which
is obtained by dividing the distance by the relative vehicle speed,
is less than a second threshold value Th2. Using different analyses
provides enhanced target discrimination.
[0166] (11) The controller 50 regulates a reaction force from an
accelerator pedal 62. Since the driver is in engagement with the
accelerator pedal 62, risk RP1 or RP2 can be transmitted to the
driver without any failure.
[0167] (12) The controller 50 regulates not only a reaction force
from the accelerator pedal 62, but a reaction force from the brake
pedal 92. The reaction force from the brake pedal 92 is reduced as
the risk RP1 or RP2 become great, assisting the driver in operating
the brakes by stepping on the brake pedal 92.
[0168] With reference now to FIGS. 31 to 33, another embodiment of
a system, generally denoted by reference numeral 2, according to
the present invention is described.
[0169] This embodiment is substantially the same as the previously
described embodiment illustrated in FIGS. 1 to 30. However, this
embodiment is different from the previously described embodiment in
that a scene recognition device 8A includes an environment
recognition device 30. The environment recognition device 30 is,
for example, a navigation system, and detects whether or not a
tunnel or curve is in the path of a vehicle 5. The environment
recognition device 30 provides environment information to a
controller 50A.
[0170] The block diagram of FIG. 32 illustrates the controller 50A.
The controller 50A is substantially the same as the controller 50
of the previously described embodiment except that a modified
weighting device 53A is used instead of the weighting device 53. At
the modified weighting device 53A, a weighting multiplier K is
determined based on environment information provided by the
environment recognition device 30. In this embodiment, the
weighting device 53A performs a weighting of second accelerator
pedal and brake pedal reaction force values Fa2 and Fb2 determined
versus a second or transient risk RP2 in response to environment
information from the environment recognition device 30.
[0171] In this embodiment, the main routine, including the
sub-routines, used in the previously described embodiment may be
used if the "weighting (S500)" sub-routine of FIG. 15 is replaced
by a "weighting (S500A)" sub-routine of FIG. 33. This sub-routine
is executed at step S500 of the main routine shown in FIG. 10.
[0172] In FIG. 33, at step S511, a controller 50A determines
whether or not there is a tunnel or curve in front of the vehicle
5. If this is the case, the routine proceeds to step S512. In the
presence of a tunnel or curve in front of the vehicle 5, the driver
is likely to keep less attention to the preceding vehicle than in
the absence thereof. Thus, a weighting multiplier K is gradually
increased to a predetermined value K0 that is greater than 1 (for
example, K0=1.4). At step 512, the controller 50A determines
whether or not the predetermined value K0 is greater than or equal
to the value given by adding a predetermined increment .DELTA.K to
the multiplier K_z, which was given in the previous cycle.
[0173] If, at step S512, K0 is greater than or equal to the value
(K_z+A K), the routine proceeds to step S513. At step S513, the
controller 50A sets the multiplier K to (K_z+.DELTA.K). If the
result of interrogation at step S513 is negative, the routine
proceeds to step S514. At step S514, the controller 50A sets the
multiplier K to the predetermined value K0. If the result of
interrogation at step S511 is negative, the routine proceeds to
step S515. At step S515, the controller 50A sets the multiplier K
to 1.
[0174] Using the multiplier K that has been set as mentioned above,
the controller 50A performs a weighting of the reaction force
values Fa2 and Fb2 that have been determined versus the second or
transient risk RP2. The weighting is performed by multiplying K
with the reaction value Fa2 to give FA2 and multiplying K with the
reaction value Fb2 to give FB2.
[0175] According to this embodiment, the controller 50A performs a
weighting of the second reaction force values Fa2 and Fb2 that have
been determined versus second or transient risk RP2 upon
recognition that there is a tunnel or curve in front of the vehicle
5. This makes it possible to clearly transmit the transient risk
RP2 to the driver when the driver likely to pay less attention to
the preceding vehicle in front.
[0176] Other examples of the surrounding environment are:
[0177] Night/day
[0178] Brightness
[0179] Weather (fine/rain or snow)
[0180] Time signal from the navigation system or a GPS receiver may
be used to determine whether it is day or night. When it is night,
the weighting multiplier K is set larger than during the day so
that the transient risk RP2 can be clearly transmitted to the
driver. An optical sensor or ON/OFF of a headlight may be used to
detect brightness. The weighting multiplier K is set larger when it
is dark than when it is bright. A rain sensor or ON/OFF of a
windshield wiper may be used to detect whether. The weighting
multiplier K is set larger when it is not fine than when it is
fine.
[0181] With reference now to FIGS. 34 to 41, another embodiment is
described. This embodiment is substantially the same as the
previously described embodiment illustrated in FIGS. 1 to 30 except
the addition of two subsystems.
[0182] As mentioned before, a controller 50B shown in FIG. 34 is
different from the controller 50 shown in FIG. 9 in that the at
least two subsystems include, in addition to the first and second
subsystems, a third subsystem 51c, 52c, 54c, and 55c, and a fourth
subsystem 51d, 52d, 54d, and 55d.
[0183] With reference to FIG. 34, the position X and azimuth angle
.theta. between each of the detected obstacle(s) and the vehicle 5,
and the vehicle speed Vh are fed to a first contact possibility
discrimination device 51c of the third subsystem and a second
contact possibility discrimination device 51d of the fourth
subsystem. They are fed also to a third risk (RP) calculation
device 52c of the third subsystem and to a fourth risk (RP)
calculation device 52d of the fourth subsystem.
[0184] In the third subsystem, the first contact possibility
discrimination device 51c determines whether or not a vehicle 5 may
come into contact with the detected obstacle by effecting a first
contact possibility discrimination based on the vehicle speed Vh of
the vehicle 5 and a distance X to the detected obstacle from the
vehicle 5. Specifically, the first contact possibility
discrimination device 51c determines that the vehicle 5 may contact
with the detected obstacle when the time headway THW is less than a
third threshold Th3. This threshold Th3 is less than the first
threshold value Th1. Upon determination that the vehicle may
contact with the detected obstacle, the first contact possibility
discrimination device 51c activates a third risk (RP) calculation
device 52c, a third reaction force calculation device 54c, and a
third repulsive force calculation device 55c. Using the illustrated
relationships in FIGS. 19 and 20, the third reaction force
calculation device 54c determines, as variables, a third
accelerator pedal reaction force value FA3 versus the third risk
RP3 and a third brake pedal reaction force value FB3 versus the
third risk RP3. Using the illustrated relationship in FIG. 22, the
third repulsive force calculation device 55c determines, as a
variable, a third repulsive force value Fc3 versus the third risk
RP3.
[0185] In the fourth subsystem, the second contact possibility
discrimination device 51d determines whether or not the vehicle 5
may come into contact with the detected obstacle by effecting a
second contact possibility discrimination based on the relative
vehicle speed Vr and the distance X. Specifically, the second
contact possibility discrimination device 51d determines that the
vehicle 5 may contact with the detected obstacle when the time to
collision TTC is less than a fourth threshold value Th4 that is
less than the second threshold value Th2. Upon determination that
the vehicle may contact the detected obstacle, the second contact
possibility discrimination device 51d activates a fourth risk (RP)
calculation device 52d, a fourth reaction force calculation device
54d, and a fourth repulsive force calculation device 55d. The
fourth risk calculation device 52d determines a fourth risk RP4
from the detected obstacle upon determination, by the second
contact possibility discrimination device 51d, that the vehicle 5
may come into contact with the detected obstacle. Using the
illustrated relationships in FIGS. 19 and 20, the fourth reaction
force calculation device 54d determines, as variables, a fourth
accelerator pedal reaction force value FA4 versus the fourth risk
RP4 and a fourth brake pedal reaction force value FB4 versus the
fourth risk RP4. Using the illustrated relationship in FIG. 22, the
fourth repulsive force calculation device 55d determines, as a
variable, a fourth repulsive force value Fc4 versus the fourth risk
RP4.
[0186] Determination of the third risk RP3 is allowed during a
portion of the state period provided by the first target
discrimination device 51a. Determination of the second risk RP2 is
allowed during a portion of the transient period provided by the
second target discrimination device 51b.
[0187] The third and fourth accelerator pedal reaction force values
FA3 and FA4 are fed to a reaction force selection device 56 in
addition to the first and the weighted second accelerator pedal
reaction force values FA1 and FA2. The third and fourth brake pedal
reaction force values FB3 and FB4 are fed to the reaction force
selection device 56 in addition to the first and the weighted
second brake pedal reaction force values FB1 and FB2. Following a
predetermined rule, the reaction force selection device 56 selects
an appropriate one of the first to fourth accelerator pedal
reaction force values FA1, FA2, FA3, FA4 and provides the selected
one, as an accelerator pedal reaction force (APRF) indicative final
variable FA. The final variable FA is fed to an accelerator pedal
reaction force controller 60 (see FIG. 1). In the same manner, the
reaction force selection device 56 selects one of the first to
fourth brake pedal reaction force values FB1, FB2, FB3, FB4 and
provides the selected one as a brake pedal reaction force (BPRF)
indicative final variable FB. The final variable FB is fed to a
brake pedal reaction force controller 90 (see FIG. 1).
[0188] The third and fourth repulsive force values Fc3 and Fc4 are
fed to a repulsive force selection device 57 in addition to the
first and second repulsive force values Fc1 and Fc2. The repulsive
force selection device 57 selects an appropriate one of the first
to fourth repulsive force values Fc1, Fc2, Fc3, Fc4, and provides
the selected one, as a repulsive force (RF) indicative final
variable Fc. The final variable Fc is fed to a correction amount
calculation device 58.
[0189] In the exemplary embodiment, the controller 50B implements
all of the devices of the block diagram shown in FIG. 34 in
software.
[0190] FIG. 35 is a flow chart of a main control routine
illustrating the operation of the controller 50B. In the
embodiment, the controller 50B repeats execution of the main
control routine at regular intervals of, for example, 50
milliseconds.
[0191] With reference also to FIG. 10, it will be understood that
the main control routines of FIG. 35 and FIG. 10 have like steps
S100, S200, S300, S500, S1000, S1100, and S1200. Further, as the
discussion proceeds, it will be understood that steps S450, S650,
S750, S850 and S950 of the control routine of FIG. 35 are very
similar to the steps S400, S600, S700, S800 and S900 of the control
routine of FIG. 10, respectively. However, the main control routine
of FIG. 35 has a new step S350.
[0192] In FIG. 35, the controller 50B performs a reading operation,
at step S100, recognizes the state of obstacle(s) relative to the
vehicle 5, at step S200, and executes a target discrimination
sub-routine shown in FIG. 11, at step S300, to determine whether or
not the detected obstacle is a target obstacle.
[0193] At step S350, the controller 50B executes a contact
possibility discrimination sub-routine of FIG. 36.
[0194] Referring to the contact possibility discrimination
sub-routine of FIG. 36, at step S351, the controller 50B determines
whether or not the time headway THW between the detected obstacle
and the vehicle 5 is greater than or equal to the third threshold
value Th3 (Th3<Th1). If this is the case, that is, THW is not
less than Th3, the controller 50B determines that the vehicle 5 may
not come into contact with detected obstacle, and sets a THW
contact-possibility flag Flg_thw1 to 0 (Flg_thw1=0) at step S352.
If, at step S351, the time headway THW is less than Th3, the
controller 50B determines that the vehicle 5 may come into contact
with the detected obstacle, and sets the THW contact-possibility
flag Flg_thw1 to 1 (Flg_thw1=1) at step S353. After step S352 or
S353, the routine proceeds to step S354.
[0195] At step S354, the controller 50B determines whether or not
the time to collision TTC between the detected obstacle and the
vehicle 5 is greater than or equal to the fourth threshold value
Th4 (Th4<Th2). If this is the case, that is, TTC is not less
than Th4, the controller 50B determines that the vehicle 5 may not
come into contact with the detected obstacle, and sets a TTC
contact-possibility flag Flg_ttc1 to 0 (Flg_ttc1=0) at step S355.
If, at step S354, the time to collision TTC is less than Th4, the
controller 50B determines that the vehicle 5 may come into contact
with the detected obstacle, and sets the TTC contact-possibility
flag Flg_ttc1 to 1 (Flg_ttc1=1) at step S356. After step S355 or
S356, the routine proceeds to step S450 (see FIG. 35).
[0196] At step S450, the controller 50B executes a risk (RP)
calculation sub-routine of FIG. 37. The sub-routines of FIGS. 37
and 14 have steps S401, S402, S403, S404, S405, S406, S407, and
S408 in common. For brevity, description on these steps is hereby
omitted.
[0197] In FIG. 34, at step S409, the controller 50B determines
whether or not the THW contact-possibility flag Flg_thw1 is equal
to 1. If this is the case, the routine proceeds to step S410
because the vehicle 5 may come into contact with the detected
obstacle.
[0198] At step S410, the controller 50B determines an unstressed
length L3 of a third imaginary elastic body using the third
threshold value Th3 and the vehicle speed Vh. The unstressed length
L3 may be expressed as: L3=Th3.times.Vh (Equation 11)
[0199] At step S411, the controller 50B determines the third risk
RP3, which may be expressed as: RP3=k3.times.(L3-X). (Equation
12)
[0200] where: k3 is a spring constant of the third imaginary
elastic body.
[0201] If, at step S409, the THW contact-possibility flag Flg_thw1
is 0, the routine proceeds to step S412 because the vehicle 5 may
not come into contact with the detected obstacle. At step S412, the
controller 50B sets the third risk RP3 to 0 (RP3=0). The first risk
RP3 may be called a stable risk because it grows during a portion
of the stable period. After step S411 or S412, the routine proceeds
to step S413.
[0202] At step S413, the controller 50B determines whether or not
the TTC target flag Flg_ttc1 is equal to 1. If this is the case,
the routine proceeds to step S413 because the vehicle 5 may come
into contact with the detected obstacle.
[0203] At step S414, the controller 50B determines an unstressed
length L4 of a fourth imaginary elastic body using the fourth
threshold value Th4 and the relative vehicle speed Vr. The
unstressed length L4 may be expressed as: L4=Th4.times.Vr (Equation
13)
[0204] At step S415, the controller 50B determines the fourth risk
RP4, which may be expressed as: RP4=k4.times.(L4-X). (Equation
14)
[0205] where: k3 is a spring constant of the fourth imaginary
elastic body.
[0206] If, at step S413, the TTC contact-possibility flag Flg_ttc1
is 0, the routine proceeds to step S416 because the vehicle 5 may
not come into contact with the detected obstacle. At step S416, the
controller 50B sets the fourth risk RP4 to 0 (RP4=0). The fourth
risk RP4 may be called a transient risk because it occurs during a
portion of the transient period. After step S415 or S416, the
routine proceeds to step S500 (see FIG. 10).
[0207] At step S500, the controller 50 executes a weighting
sub-routine of FIG. 15.
[0208] At step S650, the controller 50B executes a reaction force
calculation sub-routine of FIG. 38 to determine, as variables,
first to fourth accelerator and brake pedal reaction force values
FA1 & FB1, FA2 & FB2, FA3 & FB3, and FA4 & FB4
[0209] The sub-routines of FIGS. 38 and 18 have steps S601, S602,
S603, S604, and S605 in common. For brevity, description on these
steps is hereby omitted.
[0210] In FIG. 38, at step S611, the controller 50B determines a
third accelerator pedal reaction force value FA3 versus the third
or stable risk RP3 by using the relationship illustrated in FIG.
19.
[0211] At step S612, the controller 50B determines a fourth
accelerator pedal reaction force value FA4 versus the fourth or
transient risk RP4 by using the relationship illustrated in FIG.
19.
[0212] At step S613, the controller 50B determines a third brake
pedal reaction force value FB3 versus the third or stable risk RP3
by using the relationship illustrated in FIG. 20.
[0213] At step S614, the controller 50B determines a fourth brake
pedal reaction force value FB4 versus the fourth or transient risk
RP4 by using the relationship illustrated in FIG. 20.
[0214] After determining the first to fourth accelerator and brake
pedal reaction force values FA1 & FB1, FA2 & FB2, FA3 &
FB3, and FA4 & FB4 at step S650, the routine proceeds to step
S750.
[0215] At step S750, the controller 50B executes a repulsive force
calculation sub-routine of FIG. 39. The sub-routines of FIGS. 39
and 21 have steps S701 and S702 in common.
[0216] In FIG. 39, at step S703, the controller 50B determines, as
a variable, a third repulsive force value Fc3 versus the third or
stable risk RP3 by using the relationship illustrated in FIG.
22.
[0217] At the next step S704, the controller 50B determines, as a
variable, a fourth repulsive force value Fc4 versus the fourth or
transient risk RP4 by using the relationship illustrated in FIG.
22.
[0218] After determining the repulsive force values Fc1, Fc2, Fc3,
and Fc4 at step S750, the routine proceeds to step S850.
[0219] At step S850, the controller 50B executes a reaction force
selection sub-routine of FIG. 40.
[0220] In FIG. 40, at step S811, the controller 50B selects the
greatest one, in absolute value, of a set of accelerator pedal
reaction force values, including reaction values FA1, FA2, FA3 and
FA4, and provides the selected one, as an accelerator pedal
reaction force indicative final variable FA,
[0221] At step S812, the controller 50B selects the smallest one,
in absolute value, of a set of brake pedal reaction force values,
including reaction values FB1, FB2, FB3, and FB4, and provides the
selected one, as a brake pedal reaction force indicative final
variable FB.
[0222] At step S950, the controller 50B executes a repulsive force
selection sub-routine of FIG. 41.
[0223] In FIG. 41, at step S911, the controller 50B selects the
largest one among a set of repulsive force values including the
first to fourth repulsive force values Fc1, Fc2, Fe3, and Fe4, and
provides the selected one, as the final variable Fc.
[0224] After step 950, the controller 50B proceeds to steps S1000,
S1100, and S1200.
[0225] As described above, the first contact possibility
discrimination device 51c determines the possibility whether or not
the vehicle 5 may come into contact with the preceding vehicle
based on the distance X and vehicle speed Vh. Third risk (RP)
calculation device 52c determines the third or state risk RP3 upon
determination that the vehicle 5 may come into contact with the
preceding obstacle. The third reaction force calculation device 54c
determines the accelerator and brake pedal reaction force values
FA3 and FB3 based on the third or state risk RP3. The second
contact possibility discrimination device 51d determines the
possibility whether or not the vehicle 5 may come into contact with
the preceding vehicle based on the distance X and relative vehicle
speed Vr. Fourth risk (RP) calculation device 52d determines the
fourth or transient risk RP4 upon determination that the vehicle 5
may come into contact with the preceding obstacle. The fourth
reaction force calculation device 54d determines the accelerator
and brake pedal reaction force values FA4 and FB4 based on the
fourth or transient risk RP4. The reaction force selection device
56 selects the largest one, in absolute value, of a set of
accelerator pedal reaction force values, including the first to
fourth reaction force values FA1 to FA4, and provides the selected
one, as an accelerator pedal reaction force indicative final
variable FA. The reaction force selection device 56 selects the
largest one, in absolute value, of brake pedal reaction force
values FB1 to FB4, and provides the selected one, as a brake pedal
reaction force indicative final variable FB.
[0226] After determining a third repulsive force value Fc3 based on
the third or stable risk RP3 and a fourth repulsive force value Fc4
based on the fourth or transient risk RP4, the repulsive force
selection device 57 selects the largest one, in absolute value, of
a set of repulsive force values including the first to fourth
repulsive force values Fc1 to Fc4, and provides the selected one,
as a repulsive force indicative final variable Fc.
[0227] In the embodiments, the reaction force control and the
driving force control have been carried out. The present invention
is not limited to this example. Use of only one of the reaction
force control and the driving force control is possible.
[0228] In the embodiments, the accelerator pedal reaction force
control and brake pedal reaction force control have been carried
out. The present invention is not limited to this example. Use of
only one of the accelerator pedal reaction control and brake pedal
reaction force control is possible.
[0229] While the best modes for carrying out the invention have
been described in detail, those familiar with the art to which the
present invention relates will recognize various alternative
designs and embodiments for practicing the invention as defined by
the following claims.
[0230] As set forth above, according to a method and system for
assisting a driver operating a vehicle traveling on a road of the
present invention, transient information that a vehicle is
approaching an obstacle can be provided to a driver as well as
stable information that the vehicle is following the obstacle in
front of the vehicle. Therefore, such a method and system is
applicable to a variety of moving bodies such as automotive
vehicles, with its application being expected in wide ranges.
* * * * *